Fig 1: Expression of Alk1 proteins in HA-ECs and cAVM-ECs. (A–D) Immunofluorescent staining to detect the Alk1 protein expressed in HA-ECs and cAVM-ECs. (A–C) In HA-ECs, (A) Alk1 protein was stained by Green fluorescent, (B) nuclei was stained by DAPI in Green fluorescent; (C) merge; (D–F) In cAVM-ECs, (D) Alk1 protein was stained by Green fluorescent, (E) nuclei was stained by DAPI in Green fluorescent; the fluorescence intensity in cAVM-ECs was obviously lower than in HA-ECs; (F) merge. Scale bar = 200 μm; (G) Detect the expression of Alk1 by Western blot, (H) expression of Alk1 proteins in the HA-ECs cultures were significantly higher than that in cAVM-ECs in vitro (∗p < 0.05).